Textile materials for power transmission and conveyor belting



Dec. 30, 1958 G. E. WATTS ETAL 2,866,483

TEXTILE MATERIALS FOR POWER RANSMISSION AND CONVEYOR BELTING Filed May 31, 1955 [her-i Ernest Inventors m mmzh hr m United States Patent TEXTILE MATERIALS FOR POWER TRANS- MISSION AND CONVEYOR BELTIYG Gilbert Ernest Watts, Hull, Sidney Beetham Hainsworth, Elloughton, near Brough, and Hugh Joseph Perry, Hull, England, assignors to J. H. Fenner & Co. Limited, Hull, England, a British company Application May 31, 1955, Serial No. 512,068 Claims priority, application Great Britain June 1, 1954 i 3 Claims. (Cl. 139-412) This invention relates to textile materials for power transmission and conveyor belting and is particularly concerned with the latter.

The belting and conveyor bands used for conveying material such as coal, are normally fabricated from impregnated textile material and are frequently damaged by hard pieces of the coal or associated sharp stones or rock of abnormal size fouling an-obstruction and piercing the belt, resulting in a longitudinal tear therein. Such tears may be very extensive and cause high replacement costs. It has been proposed to overcome this difficulty by utilising weft yarns all of which have a high breaking tension e. g. of material such as nylon, these yarns being disposed across the width of the belt. While this method reduces the tendency for tears to occur along the length of the belt, the cost of the belting is greatly increased due to the relatively high cost of yarn such as nylon. It has also been proposed to incorporate metallic reinforcements at spaced intervals across the width of the belt but the inclusion of such metallic reinforcements renders more difiicult the fabrication of the belt and if such metallic reinforcements become exposed, and especially if they fray, e. g. as in the case of wire cord, then the fire hazard due to frictional sparking is greatly enhanced.

An object of the present invention is to provide an improved textile fabric for conveyer belting in which the resistance to extensive longitudinal tears is considerably reduced.

According to the present invention, yarn groups of increased resistance to rupture and of suitable weaving characteristics, are disposed across the width of a strip of textile fabric at intervals along the length thereof, yarns across the width of the strip between the aforementioned yarn groups of increased rupture resistance being normal yarns of rupture resistance lower than that of the yarn groups of increased rupture resistance. Since, where the fabric is used in belting, the Warp of the fabric is normally parallel to the length of the belting, the yarns of increased rupture resistance will normally be weft yarns.

The ratio of the length of a section of the belt in which normal weft yarns are employed to the length of a section in which the yarns of increased rupture resistance or strong yarns are employed may vary between 5 to 1 and 20 to 1. For example, the normal yarn may be used to weave 36" lengths of the belt, these being separated by 2" to 3" lengths of the strong yarn.

Where multiple ply textile fabric belts are employed, the sections of the plies containing the strong yarns should be superimposed to attain the maximum increased tear resistance. If desired however, only the outer plies or one outer ply need contain strong yarns.

The expression suitable weaving characteristics is intended to exclude those yarns of low shear resistance which become weakened or frayed by the crossing action of the warp yarns over the weft yarns during Weaving.

The yarns of increased rupture resistance may possess greater tensile strength than the cotton yarns normally "ice example, the sections containing strong yarns may have more picks per unit length than the sections of the belt containing normal yarns, or may have thicker weft yarns. Again the sections containing strong yarns may consist of normal weft yarns reinforced by additional weft yarns of stronger materials.

In a strip of fabric primarily intended for the formation of conveyor belting, the normal yarns may have a breaking load of from 35 to lbs. and a loop-breaking load not less than 35 lbs. while the yarns of increased rupture resistance have a breaking load not less than lbs. and a loop-breaking load not less than 75 lbs.

A preferred form of weave employed in applying the present invention to a multiple ply textile fabric is that in which the weft threads, both normal and strong, are bound by warp threads, each of which passes over or under a weft thread in one ply and in a first column of said weft threads and under or over a weft thread in an adjacent ply and in a second column of said weft threads, said second column of weft threads being separated from said first column of weft threads by at least one intermediate column of weft threads.

The invention is particularly advantageous when applied to solid Woven belts, in which all plies are progressively Woven, and in practice fabrication of these is carried out by filling the shuttle with one supply of strong yarn to weave one section and then changing to normal yarn to weave the adjacent section.

It is customary in solid woven belting structures for the weft yarn to pass from one ply to another at the belt edges, and an advantage which arises from the inclusion of the aforementioned strong yarns is that the belt edges are very securely bound at regularly spaced intervals.

If the normal belt edge becomes somewhat weakened by Wear and starts to fray, or if the edge warp yarns should be caught by some obstruction in use, and the belt edge starts to rip back, the very secure binding in the sections Where the strong weft yarns are used, tends to stop the rip and largely minimises the damage. This is a most valuable feature, since when once the belt edge has been removed from a conventional solid woven belting structure, the warp yarns at the damaged edge have only a low measure of resistance to being stripped out, and therefore such a belt can suffer severe damage and be greatly reduced in width.

In practice, if, due to an obstructing object, a slit does occur in a belt fabricated in accordance with the invention, it normally extends only as far as an adjacent section containing strong yarns where opposition by the strong yarns to the obstructing object causes the object to be forcibly removed or causes the belt to tear across instead of longitudinally. Thus, only the maximum length of the distance between adjacent sections containing strong yarns can be lost due to slit damage, and the general damage to the belting is greatly reduced. Similarly, with stripping back of warp yarns from the belt edge, the stripping normally extends only as far as an adjacent section containing strong'yarns, where it is halted.

The invention will now be further described with reference to the accompanying drawings in which:

Fig. 1 is a plan view of a strip of textile fabric according to the invention,

Fig. 2 is a section taken along the line 11-11 of Fig. l, and

Fig. 3 is an edge view of part of a strip of textile fabric according to the invention.

Referring firstly to Figs. 1 and 2, a strip of three ply textile fabric 4 consists of alternating sections 4a and 4b in which weft threads are disposed across the width of the strip and warp threads are disposed parallel to the length of the strip. Each section 4a is 36" in length and each section 4b is 2 in length, the number of picks per inch per ply throughout the strip being S/inch. Weft threads 5 have greater tensile strength than cotton weft threads 6. Warp threads 7 bind weft threads 5 and 6 in the manner shown. The strip may be impregnated with polyvinyl chloride, rubber or other impregnants.

In Fig. 3, the disposition of weft threads 5 binding the edges of the strip is shown, portions 5a (full lines) being at the near edge and portions 5b (dotted) at the far edge. Portions 50 at the junctions of portions 5a and 5b represent the passing of the weft across the width of the belt. Warp threads 7 are shown by single lines for the sake of clarity.

The following table illustrates the effectiveness of a number of different types of weft thread 5, and includes comparative figures for a strip having the weave of Fig. 2 but omitting sections 4b.

also be produced by using a greater weave density, the weaving operation is more diflicult than when using strong yarns of increased tensile strength.

We claim:

1. A power transmission and conveyor belting of uniform thickness and flexibility comprising an elongated strip of impregnated textile fabric including a plurality of first weft sections of cellulosic yarns forming a major portion of said belting, a plurality of relatively narrow, tear-resisting second weft sections of thermoplastic polymeric material individually alternating in series with said first sections, said yarns in said second sections having greater tear-resistance than but substantially the same diameter as the yarns in said first sections, and warp yarns binding said weft yarns in said first and second sections, the ratio of the length of said first sections to said second sections lying between 5:1 to 20:1, and the number of weft yarns per unit length of strip being the same in said first and second sections.

2. The power transmission and conveyor belting of uniform thickness and flexibility as defined in claim 1, wherein said cellulosic weft yarns in said first sections are Yards Breaking Loop Belt Weft Threads 6 Weft Threads 5 per lb. Load, Breaking Tearing lbs. Load, lbs. Test, lbs.

9s/25 cotton 306 48 47 104 Do. /45 cotton 169 79 67 185 Do. Wis/1G nylon, worsted sp 263 121 102 460 N Dol 7%s/16 polyester fiber. worsted sp1m 260 105 80 478 N Du 210 denier/G/ifi nylon, filament 206 290 Above 480 N Do 250 denier/8/11 polyester fiber, filamenL. 192 286 Above 110 450 N Do 1050 denier/2H Tenasco, filament..- 178 93 450 F His/20 fibre, worsted spun l. 211 75 63 When the 9s/45 cotton was used as weft threads 5, the load required to tear the belt along its length rose from 104 lbs. to lbs; when the much stronger nylon and polyester fiber yarns were used the figure rose to 450-480 lbs. and the belt tore across its width (indicated by N) i. e. the tear along the belt in the region using 9s/25 cotton weft changed direction to across the belt on reaching the strong region. The Tenasco yarn appeared to be an intermediate case, where the warp and weft resistance to tearing was about equal, for here the tear proceeded at approximately 45 (F). It would thus appear that the warp tearing strength is about 450-480 lbs. and on using a weft which gives a greater figure than this, the tear is deflected across the warp.

The loop breaking load gives a measure of the shear resistance of the yarns; it is half the value obtained when a yarn is formed into a loop and another length of the yarn is looped through this and the two lengths then strained apart. The precise values for the filament nylon and polyester fiber could not be obtained as they were above the capacity of the test machine.

It will be appreciated that while the strong yarns may cotton yarns and said thermoplastic polymeric weft yarns in said second sections are nylon yarns.

3. The power transmission and conveyor belting of uniform thickness and flexibility as defined in claim 1, wherein said cellulosic weft yarns in said first sections are cotton yarns and said thermoplastic polymeric weft yarns in said second sections are yarns of polyester fiber.

References Cited in the file of this patent UNITED STATES PATENTS 

